Cab dome light and third brake light staying on
 

Hi all, I've got a 2008 XL 4.2 manual that's acting up in a funny way.

So yesterday after getting into the truck to head to work, I noticed that my dome light was staying on after I closed the door and started the engine (and yes I switched through all three positions in the dome light...) I thought it was a little odd, and maybe the door latch was stuck, so I tried opening and closing the door. I noticed that when opening/closing the door, the "door open" light went on/off on the dash, basically doing what it was supposed to, but the dome light was staying on. Additionally, the chime I get for leaving headlights on with a door open still works correctly (ie, chiming with door open, stopping when door is closed.) So I don't think it is something to do with the door latch sensor, though I did give it a nice dousing of WD40 just in case anything was sticky (the only other threads I found were people having trouble with the door latch sensor)...

The only thing I have changed recently was the addition of an aftermarket head unit about three weeks ago, but I can't imagine how that would have impacted the convenience lights. Also it's a little colder here in Houston than it has been for the last couple weeks (down into the high 30's low 40's overnight.)

Long story short:

• Door sensor seems to be working - "door open" light turns on and off correctly, headlight chime works correctly
• Dome and third brake light stay on indefinitely, but do seem to eventually turn off
• New aftermarket head unit - connected with harnesses to original wiring, only taps I put in were for reverse and parking sensors. I'm just wondering if maybe the "accessory wiring" could be on the same circuit as lighting and causing the lights to turn off slower?

Any idea what could be suspect in this case?
Also, could anyone link me to wiring diagrams for the 2008 4.2 XL so I can see what else might be on that circuit? Thanks!

Is your dimmer switch clicked all the way up ? If it is ..its doing what its supposed to do.

Hmm I'll have to check on that - didn't think about that! Maybe I somehow bumped it when doing the head unit or something.

edit: Are you talking about the headlight switch on the left of the steering wheel? If so then yes, I made sure that is off - per original post, I turned headlights on/off with the door open/closed, and I got the chiming when the door was open with the lights on, but no chime with the door closed/lights on, or door open/lights off.

The cabin dimmer wheel.. next to the head light switch.. if you run the wheel all the way up.. it clicks on for cargo light and dome light.

Jumped in the truck just before lunch and realized that there is that dimmer wheel switch. In the four years of having the truck I don't think I've once noticed it being there... :blink: but yep that did it. I just have bonus WD40 smell in my cab now from doing the latches!

LOL... glad you got it solved without having to toss parts at it. bonus WD-40 air freshener.

I did that once...
Except all my dash lights were dim. Took out the multimeter and then it hit me...lol

Yep... Light travels faster than sound.

ha
ha
ha

You Da man Luke...